Vacuum discharge tube



g. 17, 1954 N. wARMoLTz VACUUM DISCHARGE TUBE Filed NOV. 6. 1951INVENTOR Nicolaas Wormolz Sym Patented Aug. 17, 1954 2,686,888 VACUUMDISCHARGE TUBE Nicolaas Warmoltz, Eindhoven, Netherlands, as-

signor to Hartford National Bank and Trust Company, Hartford, Conn., astrustee Application November 6, 1951, Serial No. 255,096

Claims priority, application Netherlands December 4, 1950 in which anincandescent cathode is arranged close to the anode by means of a thininsulator.

According to the invention, in a high-vacuum` discharge tube whichcomprises at least an anode` and a cathode arranged on oppositesides ofand in contact with an insulator, the cold cathode, which has a smallerlength than the anode, is arranged in contact with the insulator in suchmanner that the border line cathode-insulatorvacuum has the anode facingit on the opposite side of the insulator. This arrangement permits arectifying effect to be obtained, since the field intensity on theborder line cathode-insulatorvacuum is higher than that on the borderline anode-insulator-vacuum. The anode preferably has a greater lengththan the insulator, so that the mutual conductance of the discharge tubeis substantially reduced in the conductive direction, Border linecathode-insulator-vacuum is dened as the region at the terminus of acold cathode mounted on an insulating member disposed in an evacuatedenvelope.

The longer the border line cathode-insulatorvacuum the more current thetube is capable of passing at a predetermined voltage. If there are onone side of the insulator several border lines cathode-insulator-vacuumbetween which the insulator is not interrupted, it is advisable toarrange at a small distance therefrom a supplementary electrode whichmay function as an auxiliary anode or as a control grid.

The invention will now be described more fully with reference to theaccompanying drawing, in which:

Figs. 1 and 2 show an electric discharge tube according uto theinvention in its simplest form.

Fig. 3 shows a discharge tube provided with an auxiliary electrode.

Figs. 4 and 5 show two sectional views of a tube according to theinvention having a low mutual conductance, and

Figs. 6, '7 and 8 respectively show alternative embodimentsthereof.

Referring to Fig. 1, the tube comprises a glass bulb l, an anode rod 2several mms. thick which is coated with a glass layer 3 of thickness0.15 mm. and a cathode formed by a metal layer 4.

The tube shown in Fig. 2 is similar to that of Fig. 1 except for thecathode which is constituted by a ring so that two circular border linescathode-insulator-vacuum are formed.

In the tube shown in Fig. 3 several rings 4 are mounted on the insulator3 and a cylindrical auxiliary electrode 5 is provided in order that theelectrons emanating on the cathode border lines may be discharged morereadily.

Fig. 4 is a sectional view taken at right angles to the axis of theelectrode system, 2 designating the anode rod, 3 the insulating layerand a number of strips Which are united by a ring and'extend in thedirection of the axis of the anode.

Fig. 5 is a lateral view of this electrode system.

In the tube of Fig. 6 the cathode is formed by a conductive helix 8mounted on the insulator 3, the auxiliary anode being again designated5.

In the tube of Fig. 7, the anode is constituted by a flat plate 9 coatedwith a glass layer ID having mounted on it a number of parallel strips lI. The same arrangement is made both on the front and on the rear of theplate, and Fig. 8 is a crosssectional View of this electrode system, |12designating the auxiliary electrode.

While the invention has been described in connection with specificexamples and applications thereof, other modifications of the inventionwill be readily apparent to those skilled in the art Without departingfrom its spirit and scope as deiined in the appended claim.

What I claim is:

A high vacuum discharge tube comprising an evacuated envelope, aninsulating member having opposite surface portions disposed Within theenvelope, a cold emissive cathode comprising a plurality oflongitudinally extending strips interconnected by a ring-shaped memberdisposed on one of said surface portions of the insulator, at

least one edge of one of said strips defining with said insulatingmember a border-line cathode insulator-vacuum and an anode disposed onthe opposite surface portion of the insulator parallel to and facing thecathode, said anode being positioned to extend beyond said border-linecathodeinsulator-vacuum.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,188,194 Moore June 20, 1916 1,955,391 Schroter Apr. 17, 19341,991,632 Scofield Feb. 19, 1935 2,223,040 Mahl Nov. 26, 1940 2,409,716Slock et a1. Oct. 22, 1946

